680 and SuperTooth II

I have a new 680 and have been trying to use it with the Blueant Supertooth II. It pairs easily but when I make a call I can get the white out bluetooth symbol and the screen says bluetooth in use but no sound comes out of the Supertooth. Occasionally it will work and then the Bluetooth symbol is repalced by a headset symbol. Are there any settings I can change or are the two devices incompatable?